Because of the ways in which CNS neoplasia is unique, it appeared to us that intra-tumor adoptive immunotherapy offered the most promise. In order to determine which population of immune cells would be most effective in retarding tumor growth, we carried out a series of Winn assays. In our first set of experiments, we determined that peritoneal exudate cells from animals that had been previously immunized against the specific tumor cell line could prevent the subcutaneous growth of this brain neoplasm. We next determined that such a cell population would in fact be as effective in retarding brain tumor growth when injected intracerebrally either alone or combined with systemic brain tumor chemotherapy. Since it would appear difficult to conceive of using peritoneal exudate cells in any form in human brain tumor immunotherapy, we next evaluated the effectiveness of lymph node cells when using adoptive immunotherapy. The results of these experiments indicated that the most effective lymph node population was that which was obtained from previously immunized rats, and in which the lymph node cells were not passed over nylon wool columns. Once again, when this cell population was injected intracerebrally, we achieved the prolongation in survival in animals harboring a 9L brain tumor. In our most recent experiments, we concluded that irradiated whole tumor cells were a better mode of antigen presentation compared to either gluteraldehyde-treated tumor cells or a KCl extract of the tumor cells. In addition, other experiments indicated that peripheral lymph node cells obtained from animals who themselves have brain tumors are at least as effective as donor cells taken from animals who do not themselves harbor a brain tumor.